[clang-tools-extra] [clang-tidy] New bugprone-unsafe-format-string check (PR #168691)

[via cfe-commits]

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@@ -0,0 +1,33 @@
+// RUN: %check_clang_tidy %s bugprone-unsafe-format-string %t --\
+// RUN:  -config="{CheckOptions: {bugprone-unsafe-format-string.CustomPrintfFunctions: 'mysprintf, 1;', bugprone-unsafe-format-string.CustomScanfFunctions: 'myscanf, 0;'  }}"\
+// RUN: -- -isystem %S/Inputs/unsafe-format-string
+
+#include <system-header-simulator.h>
+
+extern int myscanf( const char* format, ... );
+extern int mysprintf( char* buffer, const char* format, ... );
+
+void test_sprintf() {
+  char buffer[100];
+  const char* input = "user input";
+
+  /* Positive: unsafe %s without field width */
+  mysprintf(buffer, "%s", input);
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: format specifier '%s' without precision may cause buffer overflow; consider using '%.Ns' where N limits output length [bugprone-unsafe-format-string]
+  
+  mysprintf(buffer, "%.99s", input);
+  /*no warning*/
+}
+
+
+void test_scanf() {
+  char buffer[100];
+
+  /* Positive: unsafe %s without field width */
+  myscanf("%s", buffer);
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: format specifier '%s' without field width may cause buffer overflow; consider using '%Ns' where N limits input length [bugprone-unsafe-format-string]
+
+  /*Negative: safe %s with field width */
+  myscanf("%99s", buffer);
+  /* no-warning */
+}
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EugeneZelenko wrote:

Please add newline.

https://github.com/llvm/llvm-project/pull/168691